1. Field of the Invention
The present invention relates to a water-based composition which includes a powdered solid, carried to be dispensed from a pressurized aerosol container.
Aerosol containers are commonly used to dispense a wide variety of consumer products including house-hold products such as pesticides, germicides, and liquid cleaners, and personal products such as deodorants, antiperspirants, and colognes. Such containers provide a convenient way for storing as well as for using products of this general type in the home or office. However, certain problems have been encountered in adapting conventional aerosol technology to dispense powdered solid products such as talcs, processed starches, pigments, silicas, powdered metals, clays and the like, which are essentially insoluble in commonly used aerosol propellants and in water. These products can only be dispensed in spray form as a solid particulate.
2. Description of the Prior Art
Most presently known compositions for carrying a powdered solid product to be dispensed from an aerosol container comprise up to 10 percent by weight of solid product, approximately 1 percent perfume, 1 percent emollient and approximately 90 percent aerosol propellant. Therefore, the amount of available product is obviously relatively small compared to other components.
Attempts to increase the amount of powdered solid product in the composition usually resulted in increased product agglomeration and compaction on standing to such a degree that normal agitation of the container would not redisperse the powder particles in their carrier. Moreover, in such cases, the container components and particularly the aerosol valve became clogged rendering the container useless. However, when the amount of powdered solid was kept at or below 10 percent by weight of the composition, these operating problems were minimized.
Yet other problems existed. For example, the propellant ordinarily used in amounts of up to 90 percent of the composition was a fluorocarbon such as fluorocarbon P-11, fluorocarbon P-12, fluorocarbon P-114 or any combination of the three. Hydrocarbon propellants, which may be more desirable in certain circumstances, were not used because they are flammable and can consequently be dangerous when employed in high concentrations.
More recently, other attempts have been made to increase the amount of powdered solid product contained in aerosol compositions. For example, U.S. Pat. No. 3,088,874 (Geary et al.) discloses a powdered aerosol system for dispensing a composition having a surfactant, a bulking agent, a non-polar liquid and a propellant combined in a certain ratio by volume. In this system, an active powder having particles of diameter of at least 15 microns can be dispensed in quantities of at least 15 percent by weight of the composition. The non-polar liquid is said to reduce the cohesive forces between the active powder particles and hence to reduce compaction to ease dispensing. Still, the compositions disclosed in the examples given in the Geary et al. Patent utilize aerosol propellant in the relatively high range of 53.2 to 68.1 percent by weight of the composition and utilize no water.
U.S. Pat. No. 2,959,325 (Beard), assigned to the assignee of the present invention, discloses a method and apparatus for dispensing dry particles. The composition which may be dispensed includes a liquid base and the powdered solid. Both components have nearly the same specific gravity in order to prevent agglomerative sedimentation of the solid. In this way, a relatively high percentage by weight of powdered solid may be included. However, the liquid, which is the propellant, is also contained in relatively large amounts.
Both the Geary et al. and Beard Patents, then, disclose aerosol compositions for dispensing a powdered solid product which also include large amounts of propellant. As noted above, the type of propellants that can be used are, therefore, limited largey to fluorocarbons. However, the yet undefined problem of atmospheric ozone reduction may render use of this category of fluorocarbon propelled products untenable in the future. The large amounts of propellant also increases the cost of the compositions.
The high concentration of propellant in these compositions produces a chilling feeling when sprayed on the skin caused by rapid evaporation of residual propellant. This effect is particularly undesirable when personal or cosmetic products are dispensed. Therefore, these compositions have certain drawbacks.
Other aerosol compositions are disclosed in U.S. Pat. Nos. 3,773,683 (Aubert); 3,568,394 (Margolis); and 2,968,628 (Reed).